Coronary Artery Bypass Graft Surgery (CABG)
(CABG, Open Heart Surgery, Bypass Surgery)
What is coronary artery bypass surgery?
Coronary artery bypass graft surgery (CABG) is a procedure used to treat coronary artery disease in certain circumstances. Coronary artery disease (CAD) is the narrowing of the coronary arteries (the blood vessels that supply oxygen and nutrients to the heart muscle), caused by a buildup of fatty material within the walls of the arteries. This buildup causes the inside of the arteries to become rough and narrowed, limiting the supply of oxygen-rich blood to the heart muscle.
One way to treat the blocked or narrowed arteries is to bypass the blocked portion of the coronary artery with another piece of blood vessel. Blood vessels, or grafts, used for the bypass procedure may be pieces of a vein taken from the legs or an artery in the chest. One end of the graft is attached above the blockage and the other end is attached below the blockage. Thus, the blood is rerouted around, or bypasses, the blockage through the new graft to reach the heart muscle. This bypass of the blocked coronary artery can be done by performing coronary artery bypass surgery.
Traditionally, in order to bypass the blocked coronary artery in this manner, the chest is opened in the operating room and the heart is stopped for a time so that the surgeon can perform the bypass. In order to open the chest, the breastbone (sternum) is cut in half and spread apart. Once the heart is exposed, tubes are inserted into the heart so that the blood can be pumped through the body during the surgery by a cardiopulmonary bypass machine (heart-lung machine). The bypass machine is necessary to pump blood while the heart is stopped and kept still in order for the surgeon to perform the bypass operation.
While the traditional "open heart" procedure is still performed and often preferred in many situations, newer, less invasive techniques have been developed to bypass blocked coronary arteries. "Off-pump" procedures, in which the heart does not have to be stopped, were developed in the 1990's. Other minimally-invasive procedures, such as key-hole surgery (performed through very small incisions) and robotic procedures (performed with the aid of a moving mechanical device), increasingly are being used.
Two other surgical improvements for persons undergoing CABG are endoscopic vein harvesting and endoscopic radial artery harvesting. In both of these procedures surgeons use an endoscope (thin surgical tube with a light and camera on the end) to locate blood vessels that will be used for bypassing the blocked coronary arteries. Veins are generally harvested from the inner thigh and calf areas of the legs, while the radial artery is harvested from the wrist.
Traditional (open) approaches involve making long surgical incisions down the inner thigh and/or calf. Research comparing traditional approaches with endoscopic methods indicates that patients generally have fewer complications, less leg pain, and shorter hospital stays with the endoscopic harvesting methods. Some persons, however, may not be eligible for these methods because of other health conditions.
Other related procedures that may be used to assess and/or treat the heart include resting or exercise electrocardiogram (ECG), Holter monitor, signal-averaged ECG, cardiac catheterization, chest X-ray, computed tomography (CT scan) of the chest, echocardiography, electrophysiological studies, magnetic resonance imaging (MRI) of the heart, myocardial perfusion scans, percutaneous transluminal coronary angioplasty (PTCA), radionuclide angiography, CT angiography, and ultrafast CT scan. Please see these procedures for additional information.
Coronary arteries of the heart
To better understand how coronary artery disease affects the heart, a review of basic heart anatomy and function follows.
The heart is basically a pump. The heart is made up of specialized muscle tissue, called the myocardium. The heart's primary function is to pump blood throughout the body, so that the body's tissues can receive oxygen and nutrients.
Like any pump, the heart requires fuel in order to work. The myocardium requires oxygen and nutrients, just like any other tissue in the body. However, the blood that passes through the heart's chambers is only passing through on its trip through the body. This blood does not give oxygen and nutrients to the myocardium. The myocardium receives its oxygen and nutrients from the coronary arteries. The coronary arteries lie on the outside of the heart and supply oxygenated blood to the heart tissue.
When the heart tissue does not receive an adequate blood supply, it cannot function as well as it should. If the myocardium's blood supply is decreased for a length of time, a condition called ischemia may develop. Ischemia can decrease the heart's pumping ability, because the heart muscle is weakened due to a lack of oxygen.
For many years, coronary artery disease (CAD) was commonly called "hardening of the arteries" and was not easily treated. However, in the last 30 years, many advances have been made in the diagnosis and treatment of cardiac diseases.
Reasons for the procedure
Coronary artery bypass surgery is performed to treat a blockage or narrowing of one or more of the coronary arteries, thus restoring the blood supply to the heart muscle.
Symptoms of coronary artery disease may include, but are not limited to, the following:
Abnormal heart rhythms
Shortness of breath
Unfortunately, there may be no symptoms of early coronary artery disease, yet the disease will continue to progress until sufficient artery blockage exists to cause symptoms and problems. If the blood supply to the heart muscle continues to decrease as a result of increasing obstruction of a coronary artery, a myocardial infarction, or heart attack, may occur. If the blood flow cannot be restored to the particular area of the heart muscle affected, the tissue dies.
There may be other reasons for your doctor to recommend coronary artery bypass surgery.
Risks of the procedure
Possible risks associated with coronary artery bypass graft surgery include, but are not limited to, the following:
Bleeding during or after the surgery
Blood clots that can cause heart attack, stroke, or lung problems
Infection at the incision site
Cardiac dysrhythmias/arrhythmias (abnormal heart rhythms)
If you are pregnant or suspect that you may be pregnant, you should notify your health care provider. If you are lactating, or breastfeeding, you should notify your health care provider.
Patients who are allergic to or sensitive to medications, contrasts dyes, iodine, or latex should notify their doctor.
There may be other risks depending on your specific medical condition. Be sure to discuss any concerns with your doctor prior to the procedure.
Before the procedure
Your doctor will explain the procedure to you and offer you the opportunity to ask any questions that you might have about the procedure.
You will be asked to sign a consent form that gives your permission to do the test. Read the form carefully and ask questions if something is not clear.
In addition to a complete medical history, your doctor may perform a complete physical examination to ensure you are in good health before undergoing the procedure. You may undergo blood tests or other diagnostic tests.
You will be asked to fast for eight hours before the procedure, generally after midnight.
If you are pregnant or suspect that you are pregnant, you should notify your doctor.
Notify your doctor if you are sensitive to or are allergic to any medications, iodine, latex, tape, or anesthetic agents (local and general).
Notify your doctor of all medications (prescription and over-the-counter) and herbal supplements that you are taking.
Notify your doctor if you have a history of bleeding disorders or if you are taking any anticoagulant (blood-thinning) medications, aspirin, or other medications that affect blood clotting. It may be necessary for you to stop some of these medications prior to the procedure.
Your doctor may request a blood test prior to the procedure to determine how long it takes your blood to clot.
Notify your doctor if you have a pacemaker.
If you smoke, you should stop smoking as soon as possible prior to the procedure. This may improve your chances for a successful recovery from surgery and benefit your overall health status.
Based on your medical condition, your doctor may request other specific preparation.
During the procedure
Coronary artery bypass graft surgery requires a stay in a hospital. Procedure may vary depending on your condition and your doctor's practices.
Generally, a coronary artery bypass surgery follows this process:
You will be asked to remove any jewelry or other objects that may interfere with the procedure.
You will be asked to remove your clothing and will be given a gown to wear.
You will be asked to empty your bladder prior to the procedure.
An intravenous (IV) line will be started in your arm or hand. Additional catheters will be inserted in your neck and wrist to monitor the status of your heart and blood pressure, as well as for obtaining blood samples. Alternate sites for the additional catheters include the subclavian (under the collarbone) area and the groin.
You will be positioned on the operating table, lying on your back.
The anesthesiologist will continuously monitor your heart rate, blood pressure, breathing, and blood oxygen level during the surgery. Once you are sedated, a breathing tube will be inserted through your throat into your lungs and you will be connected to a ventilator, which will breathe for you during the surgery.
A catheter will be inserted into your bladder to drain urine.
The skin over the surgical site will be cleansed with an antiseptic solution.
Once all the tubes and monitors are in place, incisions may be made in one or both of your legs or one of your wrists to obtain a section of vein to be used for grafts.
The doctor will make an incision (cut) down the center of the chest from just below the Adam's apple to just above the navel.
The sternum (breastbone) will be divided in half with a special operating instrument. The doctor will separate the two halves of the breastbone and spread them apart to expose the heart.
Coronary artery bypass graft surgery--on-pump procedure
In order to sew the grafts onto the very small coronary arteries, the heart must be stopped to allow the doctor to perform the very delicate procedure. Tubes will be inserted into the heart so that the blood can be pumped through your body by a cardiopulmonary bypass machine.
Once the blood has been diverted into the bypass machine for pumping, the heart will be stopped by injecting it with a cold solution.
When the heart has been stopped, the doctor will perform the bypass graft procedure by sewing one end of a section of vein over a tiny opening made in the coronary artery just above the blockage, and the other end over a tiny opening made in the coronary artery just below the blockage. If the internal mammary artery inside your chest is being used as a bypass graft, the lower end of the artery will be cut from inside the chest and sewn over an opening made in the coronary artery below the blockage.
You may have more than one bypass graft performed, depending on how many blockages you have and where they are located. After all the grafts have been completed, the doctor will examine them to make sure they are working.
Once the bypass grafts have been completed, the blood circulating through the bypass machine will be allowed back into your heart and the tubes to the machine will be removed. Your heart will be restarted.
Temporary wires for pacing may be inserted into the heart. These wires can be attached to a pacemaker and your heart can be paced, if needed, during the initial recovery period.
Coronary artery bypass surgery--off-pump procedure
Once the chest has been opened, the area around the artery to be bypassed will be stabilized with a special type of instrument.
The rest of the heart will continue to function and pump blood through the body.
The cardiopulmonary bypass machine and the perfusionist who runs it may be kept on stand-by should the procedure need to be completed on bypass.
The doctor will perform the bypass graft procedure by sewing one end of a section of vein over a tiny opening made in the coronary artery just above the blockage, and the other end over a tiny opening made in the coronary artery just below the blockage.
You may have more than one bypass graft performed, depending on how many blockages you have and where they are located.
Before the chest is closed, the doctor will examine the grafts to make sure they are working.
Procedure completion, both methods
The sternum will be pushed back together and sewn together with small wires.
The skin over the sternum will be sewn back together.
Tubes will be inserted into your chest to drain blood and other fluids from around the heart. These tubes will be connected to a suction device to keep fluids pulled away from the heart.
A tube will be inserted through your mouth or nose into your stomach to drain stomach fluids.
A sterile bandage or dressing will be applied.
After the procedure
In the hospital
After the surgery you may be taken to the recovery room before being taken to the intensive care unit (ICU) to be closely monitored. Alternatively, you may be taken directly to the ICU from the operating room. You will be connected to monitors that will constantly display your electrocardiogram (ECG or EKG) tracing, blood pressure, other pressure readings, breathing rate, and your oxygen level. Coronary artery bypass surgery requires an in-hospital stay of several days or longer.
You will most likely have a tube in your throat so that breathing can be assisted with a ventilator (breathing machine) until you are stable enough to breathe on your own. As you continue to wake up from the anesthesia and start to breathe on your own, the breathing machine will be adjusted to allow you to take over more of the breathing. When you are awake enough to breathe completely on your own and you are able to cough, the breathing tube will be removed. The stomach tube will also be removed at this time.
After the breathing tube is out, your nurse will assist you to cough and take deep breaths every two hours. This will be uncomfortable due to soreness, but it is extremely important that you do this in order to keep mucus from collecting in your lungs and possibly causing pneumonia. Your nurse will show you how to hug a pillow tightly against your chest while coughing to help ease the discomfort.
The surgical incision may be tender or sore for several days after a CABG procedure. Take a pain reliever for soreness as recommended by your physician. Aspirin or certain other pain medications may increase the chance of bleeding. Be sure to take only recommended medications.
You may be on special IV drips to help your blood pressure and your heart, and to control any problems with bleeding. As your condition stabilizes, these drips will be gradually decreased and turned off as your condition allows.
Once the breathing and stomach tubes have been removed and your condition has stabilized, you may start liquids to drink. Your diet may be gradually advanced to more solid foods as you are able to tolerate them.
When your doctor determines that you are ready, you will be moved from the ICU to a postsurgical nursing unit. Your recovery will continue to progress. Your activity will be gradually increased as you get out of bed and walk around for longer periods of time. Your diet will be advanced to solid foods as you tolerate them.
Arrangements will be made for a follow-up visit with your doctor.
Once you are home, it will be important to keep the surgical area clean and dry. Your doctor will give you specific bathing instructions. The sutures or surgical staples will be removed during a follow-up office visit, in the even they were not removed before leaving the hospital.
You should not drive until your doctor tells you to. Other activity restrictions may apply.
Notify your doctor to report any of the following:
Fever and/or chills
Redness, swelling, or bleeding or other drainage from the incision site
Increase in pain around the incision site
Your doctor may give you additional or alternate instructions after the procedure, depending on your particular situation.